1. Technical Field
The present invention relates to a stator provided with a stator core having a plurality of magnetic pole teeth arranged annularly, and a plurality of coils formed by respectively winding electrical wire around the plurality of magnetic pole teeth, and to a resolver provided with this stator and a rotor, for detecting a rotational position of a rotating shaft by detecting variations in reluctance between the rotor and the stator, and specifically relates to a stator and resolver that can negate inductive noise caused by an external field, that is passed to excitation coils to affect all detection coils wires, and that can increase angle detection accuracy.
2. Related Art
With a reluctance type resolver, there is a problem that magnetic flux and an external magnetic field generated from linked sections of the excitation coils interfere with linked sections of detection coils that are adjacent to the linked sections of the excitation coils, and cause the angle detection accuracy to be lowered. With respect to this type of problem, with a brushless type rotation detector a winding device that can suppress lowering of angle detection accuracy, formed by continuously winding coils of the same polarity in coil groups of a single phase in one direction so that a start winding and an end winding cross, and then, if winding of magnetic poles of the same polarity is completed, reversing the winding direction and winding remaining coils of an opposite polarity in the other direction so that the start winding and end winding cross, is disclosed as a detection winding device that can reduce interference by magnetic flux leaking from a rotating transformer on winding sections (refer to JP 4199826 B, for example). An embodiment of a coil device of related art disclosed in JP 4199826 B etc. will be described with reference to the drawings.
FIG. 1 shows a coil group 14 (SIN phase) that is wound around a stator 10 of a reluctance type resolver of the related art. A stator core 12 of the stator shown in FIG. 1 has 24 tooth sections provided on an internal bore, and each tooth section has an electrical wire wound around it to form a coil. The formed coils are connected in series to form a detection coil group 14. Also, each coil group 14 constitutes a phase with two teeth as a single set. Black dots shown in FIG. 1 represent locations of tooth sections where electrical wires are wound.
FIG. 2 is a development view schematically showing an arrangement pattern for the detection coil group 14 (SIN phase) using the winding method shown in FIG. 1, looking from the internal bore of the stator core 12. A method of arranging the SIN phase coil group 14 will be described using FIG. 2.
A SIN phase is constituted by a group of tooth section Nos. (3, 4), (7, 8), (11, 12), (15, 16), (19, 20), and (23, 24). Also, the group of tooth section Nos. (3, 4), (11, 12) and (19, 20) and the group of tooth section Nos. (7, 8), (15, 16) and (23, 24) have a structure with phases offset by 180°. Accordingly, an electrical wire that has been sequentially wound around tooth section Nos. 3, 8, 11, 16, 19 and 24 from an output terminal S is turned back at tooth section No. 24, sequentially wound around tooth section Nos. 23, 20, 15, 12, 7 and 4, and connected to output terminal S. The same also applies to other alphabetic characters in the following). The direction of winding the coils (Winding direction of electrical wires on each tooth section. In FIG. 2 a direction shown by an arrow beneath each tooth section.) is the same as the connection direction between coils (In FIG. 2 the direction shown by arrows above the electrical wires connecting between coils). Specifically, in the case where the connection direction between coils is anticlockwise, the winding direction of the coils is also anticlockwise looking from the inside of the stator, and in the case where the connection direction between coils is clockwise, the winding direction of the coils is also clockwise looking from the inside of the stator.
With the arrangement pattern for detection coils as shown in FIG. 2, in a SIN phase, at tooth section No. 24 where the connection direction between coils is turned back, since an undesired gap arises in one turn, the number of windings in each coil section is different, and angle detection accuracy is lowered.
Also, a schematic drawing of an equivalent circuit of a resolver looking from the primary side is shown in FIG. 5a. With a SIN phase single body, an electrical wire is sequentially wound around tooth section Nos. 3, 8, 11, 16, 19 and 24 from an output terminal S, is turned back at tooth section No. 24, sequentially wound around tooth section Nos. 23, 20, 15, 12, 7 and 4, and connected to output terminal S. As a result, electrical wires connecting between coils are reversed with respect to each other, and are adjacent, which means that it is possible to negate any influence due to an external magnetic field, and it is possible to increase angle detection accuracy. However, with this related art technology, as shown in FIG. 5a, it is not possible to negate inductive noise caused by an external magnetic field, that is passed to the excitation coils and influences all detection coils, and angle detection accuracy is lowered.
In fact, with the related art disclosed in JP 4199826 B, there is a problem in that at a tooth section where the connection direction between coils is turned back, since an undesired gap arises in one turn, the number of windings in each coil section is different, and angle detection accuracy is lowered. Also, with the technology disclosed in JP 4199826 B, there is only disclosure of detection coils, and with a simple body for each phase of the detection coils it is possible to reduce the influence of noise, but there is a problem, from FIG. 5a, that it is not possible to negate induction noise which is passed from the excitation coils and influences all detection coils. Accordingly, it is necessary to a devise a technology that can appropriately combine the excitation coils and the detection coils in order to increase angle detection accuracy.